1. Field of the Invention
This invention generally relates to an on-vehicle computer.
This invention particularly relates to an on-vehicle computer having a function of protecting a vehicular battery, for example, a function of preventing a vehicular battery from being excessively discharged by the occurrence of a problem such as a hang-up in a computer routine.
2. Description of the Related Art
A typical automotive vehicle has on-vehicle electric apparatuses such as a radio receiver and a stereophonic audio system. The on-vehicle electric apparatuses are powered by DC (direct current) energy from a vehicular battery. The positive side of the DC power is called xe2x80x9c+Bxe2x80x9d. The on-vehicle electric apparatuses are turned on and off by actuating an ACC (accessory) switch of the vehicle.
The voltage of a vehicular electric power supply formed by a vehicular battery tends to be unstable when a related vehicle is in operation. Generally, the power supply voltage repetitively drops and rises. In some cases, the power supply voltage drops below an acceptable minimum level required to normally operate on-vehicle electric apparatuses.
In the case where an on-vehicle electric apparatus is a radio receiver or a stereophonic audio system, it is good to provide the electric apparatus with a power supply backup which can deal with an excessive power-supply voltage drop for several seconds. If the power supply voltage continues to be excessively low for longer than several seconds before returning to a normal range, operation of the radio receiver or the stereophonic audio system is temporarily interrupted. After the interruption, the radio receiver or the stereophonic audio system is reset and restarted. The reset and restart spend a time interval of a few seconds to about ten seconds. Usually, the interruption and the following restart of the radio receiver or the stereophonic audio system does not cause any serious problem.
A computer system using a recording medium disc and a lengthy OS (operating system) spends a long time to start its operation after a power supply switch thereof is changed to an ON position. The starting time of such a computer system is equal to several times or several tens of times of the starting time of a radio receiver or a stereophonic audio system. Therefore, the computer system is unsuited for on-vehicle use since a power supply voltage thereto frequently drops below an acceptable minimum level while a related vehicle is in operation.
In the computer system, processes of writing and reading data into and from the recording medium disc include mechanical steps which tend to be adversely affected by mechanical vibration. Also in this regard, the computer system is unsuited for on-vehicle use. It should be noted that the on-vehicle computer is subjected to mechanical vibration while a related vehicle is in operation.
A prior-art on-vehicle computer has a casing designed to cut off vibration travelling from a vehicle body toward the inner portion of the computer. The prior-art on-vehicle computer is equipped with an auxiliary battery which maintains operation of the computer when a power supply voltage generated by a vehicular battery drops below an acceptable minimum level.
When a power supply switch of the prior-art on-vehicle computer is changed to an OFF position, the computer implements a process of ending a program and then the computer is actually turned off. In the case where a hang-up occurs in the program, the prior-art on-vehicle computer can not be turned off even when the power supply switch is changed to its OFF position. In this case, the computer continues to consume electric power at a significant rate, and there is a chance that the vehicular battery is excessively discharged. The engine of an automotive vehicle may stop if the vehicular battery is excessively discharged.
U.S. Pat. No. 5,560,023 corresponding to Japanese published unexamined patent application 8-194561 discloses a desktop computer system having a system suspend/resume capability that causes the system to enter the suspend state when the operating system""s APM driver ceases functioning. The computer system of U.S. Pat. No. 5,560,023 has a CPU, a nonvolatile storage device, volatile registers and memory data, a power management processor, a backup suspend timer and a power supply in circuit communication. The power management processor controls the regulation of power to the CPU by the power supply. The suspend/resume system is controlled by an operating system having power management control. The backup suspend timer executes independently of the power management portion of the operating system. The backup suspend timer causes the system to suspend if the power management portion of the operating system ceases functioning and the system should otherwise be suspended.
U.S. Pat. No. 5,862,394 corresponding to Japanese published unexamined patent application 10-27044 discloses a system and method of intelligently terminating power to a computing device. According to the system and method in U.S. Pat. No. 5,862,394, after a software control program starts, a timer circuit gets set. Once the timer circuit gets set, the timer proceeds until timed out. In addition, the software control program initiates an orderly shut down procedure concurrently. The software control program first starts a software shut down process and a hardware shut down process. The software control program has to be able to reset the timer circuit before it times out if additional time is needed to complete the shut down process. Finally, after the timer circuit has timed out, the orderly termination of power to the system begins. In addition, the software control program is implemented to set the timer value to time out instantly if the shut down process is complete.
It is an object of this invention to provide an improved one vehicle computer.
A first aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not a vehicle accessory switch changes to its OFF position; a hardware timer; second means for starting the hardware timer when the first means detects that the vehicle accessory switch changes to its OFF position; third means for providing a BIOS timer; fourth means for transmitting a suspending request from a BIOS to an application program and starting the BIOS timer when the first means detects that the vehicle accessory switch changes to its OFF position; fifth means for providing an application program timer; sixth means for returning a suspending permission answer from the application program to the BIOS and starting the application program timer in response to the suspending request; seventh means for generating a first turn-OFF command when an elapsed time measured by the application program timer reaches a first predetermined time interval (T2); eighth means for enabling the BIOS to generate a suspending command in response to the suspending permission answer; ninth means for generating a second turn-OFF command in cases where the sixth means continues to fail to return the suspending permission answer to the BIOS until an elapsed time measured by the BIOS timer reaches a second predetermined time interval (T1); a main computer portion; tenth means for turning off power supply to the main computer portion in response to at least one of the first turn-OFF command and the second turn-OFF command; and eleventh means for turning off power supply to the main computer portion in cases where the BIOS continues to fail to generate the suspending command and the seventh means and the ninth means continue to fail to generate the first turn-OFF command and the second turn-OFF command until an elapsed time measured by the hardware timer reaches a third predetermined time interval (T3); wherein the first predetermined time interval (T2) is longer than the second predetermined time interval (T1), and is shorter than the third predetermined time interval (T3).
A second aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not at least one of a vehicular-battery voltage and an internal-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a hardware timer; second means for starting the hardware timer when the first means detects that at least one of the vehicular-battery voltage and the internal-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; third means for providing a BIOS timer; fourth means for transmitting a shutting-down request from a BIOS to an application program and starting the BIOS timer when the first means detects that at least one of the vehicular-battery voltage and the internal-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; fifth means for returning a shutting-down permission answer from the application program to the BIOS; sixth means for enabling the BIOS to generate a shutting-down command in response to the shutting-down permission answer; seventh means for generating a turn-OFF command in cases where the fifth means continues to fail to return the shutting-down permission answer to the BIOS until an elapsed time measured by the BIOS timer reaches a second predetermined time interval (T1); a main computer portion; eighth means for turning off power supply to the main computer portion in response to the turn-OFF command; and ninth means for turning off power supply to the main computer portion in cases where the BIOS continues to fail to generate the shutting-down command and the seventh means continues to fail to generate the turn-OFF command until an elapsed time measured by the hardware timer reaches a third predetermined time interval (T3); wherein the second predetermined time interval (T1) is shorter than the third predetermined time interval (T3).
A third aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not the computer is in its suspended state; second means means for, in cases where the first means detects that the computer is in its suspended state, detecting whether or not at least one of a vehicular-battery voltage and an internal-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a hardware timer; third means for starting the hardware timer when the second means detects that at least one of the vehicular-battery voltage and the internal-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; fourth means for providing a BIOS timer; fifth means for transmitting a shutting-down request from a BIOS to an application program and starting the BIOS timer when the second means detects that at least one of the vehicular-battery voltage and the internal-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; sixth means for returning a shutting-down permission answer from the application program to the BIOS; seventh means for enabling the BIOS to generate a shutting-down command in response to the shutting-down permission answer; eighth means for generating a turn-OFF command in cases where the sixth means continues to fail to return the shutting-down permission answer to the BIOS until an elapsed time measured by the BIOS timer reaches a second predetermined time interval (T1); a main computer portion; ninth means for turning off power supply to the main computer portion in response to the turn-OFF command; and tenth means for turning off power supply to the main computer portion in cases where the BIOS continues to fail to generate the shutting-down command and the eighth means continues to fail to generate the turn-OFF command until an elapsed time measured by the hardware timer reaches a third predetermined time interval (T3); wherein the second predetermined time interval (T1) is shorter than the third predetermined time interval (T3).
A fourth aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not a vehicle accessory switch changes to its OFF position; a main computer portion including a CPU; second means for enabling the CPU to output a suspending command when the first means detects that the vehicle accessory switch changes to its OFF position; and third means for cutting off power supply to the main computer portion in cases where the CPU continuously fails to output the suspending command during a predetermined time interval after the first means detects that the vehicle accessory switch changes to its OFF position.
A fifth aspect of this invention provides an on-vehicle computer comprising a power-supply management portion operating in accordance with a first program; first means provided in the power-supply management portion for detecting whether or not a vehicle accessory switch changes to its OFF position; a main computer portion including a CPU which operates in accordance with a second program different and separate from the first program; second means provided in the power-supply management portion for feeding the CPU with information representing that the vehicle accessory switch changes to its OFF position; third means for enabling the CPU to return a suspending command to the power-supply management portion in response to the information from the second means; a power-supply controller for controlling power supply to the main computer portion; and fourth means provided in the power-supply management portion for controlling the power-supply controller to cut off power supply to the main computer portion in cases where the CPU continuously fails to return the suspending command during a predetermined time interval after the first means detects that the vehicle accessory switch changes to its OFF position.
A sixth aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not a vehicular-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a main computer portion including a CPU; second means for enabling the CPU to output a shutting-down command when the first means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; and third means for cutting off power supply to the main computer portion in cases where the CPU continuously fails to output the shutting-down command during a second predetermined time interval after the first means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval.
A seventh aspect of this invention provides an on-vehicle computer comprising a power-supply management portion operating in accordance with a first program; first means provided in the power-supply management portion for detecting whether or not a vehicular-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a main computer portion including a CPU which operates in accordance with a second program different and separate from the first program; second means provided in the power-supply management portion for feeding the CPU with information representing that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; third means for enabling the CPU to return a shutting-down command to the power-supply management portion in response to the information from the second means; a power-supply controller for controlling power supply to the main computer portion; and fourth means provided in the power-supply management portion for controlling the power-supply controller to cut off power supply to the main computer portion in cases where the CPU continuously fails to return the shutting-down command during a second predetermined time interval after the first means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval.
An eighth aspect of this invention provides an on-vehicle computer comprising first means for detecting whether or not the computer is in its suspended state; second means means for, in cases where the first means detects that the computer is in its suspended state, detecting whether or not a vehicular-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a main computer portion including a CPU; third means for enabling the CPU to output a shutting-down command when the second means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; and fourth means for cutting off power supply to the main computer portion in cases where the CPU continuously fails to output the shutting-down command during a second predetermined time interval after the second means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval.
A ninth aspect of this invention provides an on-vehicle computer comprising a power-supply management portion operating in accordance with a first program; first means provided in the power-supply management portion for detecting whether or not the computer is in its suspended state; second means means provided in the power-supply management portion for, in cases where the first means detects that the computer is in its suspended state, detecting whether or not a vehicular-battery voltage continues to be lower than a predetermined reference voltage for a first predetermined time interval; a main computer portion including a CPU which operates in accordance with a second program different and separate from the first program; third means provided in the power-supply management portion for feeding the CPU with information representing that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval; fourth means for enabling the CPU to return a shutting-down command to the power-supply management portion in response to the information from the third means; a power-supply controller for controlling power supply to the main computer portion; and fifth means provided in the power-supply management portion for controlling the power-supply controller to cut off power supply to the main computer portion in cases where the CPU continuously fails to return the shutting-down command during a second predetermined time interval after the second means detects that the vehicular-battery voltage continues to be lower than the predetermined reference voltage for the first predetermined time interval.